This invention relates to electrically pacing the heart transcutaneously.
During transcutaneous, or external, electrical pacing of a patient's heart, electrical stimuli travel from the pacing apparatus' electrodes to the heart through the patient's skin and skeletal thorax muscles to stimulate the heart. Depending on the magnitude of the stimuli and the characteristics of a particular patient's skeletal muscles, the skeletal muscles may contract in response to the passage of the electrical stimuli through them. Similarly, the passage of the electrical pacing stimuli through the patient's skin may stimulate cutaneous nerves and muscles located near to the skin. This nerve stimulation and skeletal muscle contraction may feel uncomfortable to the patient, or even become painful enough to result in the patient's intolerance of extended transcutaneous heart pacing.
It has been shown (U.S. Pat. No. 4,349,030) that the skeletal muscle contractions and cutaneous nerve stimulation associated with conventional transcutaneous heart pacing may be reduced by lengthening the duration of electrical pacing stimuli to greater than five milliseconds.